Had to change the categories filter function as the original was not working - the foreach was falling over every time on the first integer in the array, only filtering for the category and none of the others.

Function inside the public_html/googlefroogle.php

Code:
function numinix_categories_check($categories_list, $products_id, $charge) {
      if ($categories_list == ''){
      if ($charge == 1) {
        return true;
      } elseif ($charge == 2) {
        return false;
      }
    } 

else 

{

$categories_array = split(",",$categories_list); 
reset($categories_array);
while (list(, $category_id) = each($categories_array)) {
   
        if (zen_product_in_category($products_id, $category_id)) {
      return true;
        return false;
        }     
}  
 } 
  }